The white line is a point of weakness where horn from 2 different sources (wall horn, sole horn) join. Dirt may become impacted here which may compromise the strength of the join, allowing infection to enter.
Risk factors:
- Subclinical 'laminitis'
- Abrasive surfaces
- Wet conditions
- Poor horn quality
- Excessive walking on hard surfaces
- Gravel
Signs on examination of foot:
- Black areas in white line (impactions)
- Tracking (up to coronary band; under-run heel; Solar Abscess)
Radical drainage is required, opening the entire draining tract, which may involve removal of quantities of hoof. A block should be placed on the other claw of the same limb. Antibiotics are indicated.